Since mid-December 1999, the Mars Orbiter Camera (MOC) onboard the
Mars Global Surveyor (MGS) spacecraft has been taking pictures of Mars
Polar Lander's landing zone near 76°S, 195°W, in hopes of
finding some evidence as to the fate of the spacecraft that went
missing during its December 3, 1999, landing attempt. To take these
pictures, the MGS spacecraft is pointed a few degrees off its normal,
nadir-looking (straight down) path. The first phase of imaging was completed
December 24, 1999, but nothing was found. A second, expanded search
was requested by the Mars Surveyor Operations Project and was begun
in early January 2000.

The MOC operations team at Malin Space Science
Systems has been busy with the Mars Polar Lander search since
December 3rd---initial efforts focused on the use of MOC as a buffer
or "storage space" for data relayed through the MGS
Mars Relay (MR)
system. It had been hoped that the Polar Lander would try to communicate
to Earth using its UHF antenna to relay data through the MGS relay system.
Data from the relay come through the MOC and are received at Malin
Space Science Systems much in the same way that pictures from MOC
are obtained. The relay effort was concluded on January 17, 2000, with
no word from the Polar Lander. Meanwhile, the MOC operations team began
to plan, command, retrieve, and analyze images designed to look for
the Polar Lander. These pictures are taken at the highest spatial
resolution possible for MOC, 1.5 meters (5 ft.) per pixel. At this
resolution, the fuselage and wings of a jumbo jet can be distinguished,
but a Polar Lander would only be a few pixels, at most, in size.

The first illustration (A, above) shows the area being searched by
MOC. All images shown here are oriented such that north is up and west
is to the left, and all are illuminated by sunlight from the upper left.
The ellipses indicate the regions in which the Polar Lander may have
touched down. The larger ellipse was derived by NASA's Langley Research
Center (LaRC); the two smaller ellipses were calculated by the Mars Polar
Lander contractor, Lockheed Martin Astronautics (LMA). The smallest ellipse
is the target that was given to the MOC team shortly after Polar Lander
recovery attempts began in mid-December 1999. All MOC images obtained
through December 26, 1999, were targeted to this smaller ellipse--- images
were taken both on the "2 a.m." and "2 p.m." sides of Mars, with better
sunlight conditions, of course, being available on the 2 p.m. side. After
the first of the year (2000), further refinement of the entry parameters
and atmospheric conditions at the time of landing allowed additional,
different trajectories to be examined. LMA's revised ellipses were offset
from the original ellipse, and LaRC's were much larger. The two larger
ellipses shown above were given to the MOC team for targeting on the 2 p.m.
side of Mars starting during the second week of January 2000.

The second figure (B, above) shows (in orange)
the area covered by MOC from mid-December
through January 17, 2000. Gaps between and within individual images have
been caused by loss of data during transmission to Earth, combined with
occasional uncertainties in spacecraft predicted positions.

The third picture (C, above) is a mosaic of the MOC images obtained
through January 17, 2000, that cover the Mars Polar Lander landing ellipses.
Available here are two views designed to fit on a page in your web browser:
one in which the 1.5 meter (5 ft) per pixel images have been shrunk to
15 meters (49 ft) per pixel, the other in which
they have been shrunk to 30 meters (98 ft) per pixel. The most obvious feature
in the mosaic is toward the lower left---about one-half of a crater-like
circular depression is seen. More than 330 square kilometers (127 sq. miles)
of south polar terrain have been imaged at 1.5 meters per pixel for this
effort.

The fourth picture (D, above) shows some samples of the variety of terrains
and textures present within Mars Polar Lander's landing zone. Each of the
six boxes shows an area of equal size. Knobs, pits, ridges, gullies, and smooth
intervening surfaces are all seen.

The task of finding the lander in these images is daunting. As shown in
our previous release,
"Mars Polar Lander: The Search Begins," December 21, 1999,
the lander is most likely to consist of only a few square pixels
within one of these images. Thus, the MOC team is basically trying to
distinguish one or two pixels from nearly 150 million. One team member
has remarked that this is like "trying to find a specific needle in...a
haystack-sized pile of needles."

No trace of either the Polar Lander or its descent system (portions of its
aeroshell or parachute) have been seen, although this is not surprising
given the resolution of MOC and illumination conditions. Indeed, recent
results show that it is very hard to distinguish a lander even if we know
where it is located (which, in the case of Polar Lander, we do not) as
shown by the January 16, 2000, image of the Mars Pathfinder landing site,
"MOC's Highest Resolution View of
Mars Pathfinder Landing Site," January 24, 2000.

MOC imaging of the Mars Polar Lander ellipses shown above (Figures A and B)
will continue through the end of January 2000, at which time the data rates
and volumes for Mars Global Surveyor and MOC become so low as to make
further imaging prohibitive.

Images credit: NASA/JPL/Malin Space Science Systems

Malin Space Science Systems and the California Institute of Technology
built the MOC using spare hardware from the Mars Observer mission. MSSS
operates the camera from its facilities in San Diego, CA. The Jet Propulsion
Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor
spacecraft with its industrial partner, Lockheed Martin Astronautics, from
facilities in Pasadena, CA and Denver, CO.